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(11) | EP 2 340 871 A3 |
(12) | EUROPEAN PATENT APPLICATION |
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(54) | Apparatus for limiting irradiation field, and linear-member driving device |
(57) An apparatus for limiting an irradiation field includes aperture leaves arranged
in a width direction thereof, the aperture leaves being controlled to be unmovable
in the width direction and movable in a driving direction substantially perpendicular
to the width direction. The apparatus causes the aperture leaves to block radiations
emitted by a source so as to provide a desired irradiation area. At least one aperture
leaf is a supporting aperture leaf having a groove at a periphery thereof. The apparatus
includes a linear member, one end of which is secured to the periphery of the supporting
aperture leaf and the linear member engages with the groove. The apparatus also includes
a restricting portion to hold the linear member between the restricting portion and
the groove such that the supporting aperture leaf is controlled to be unmovable in
the width direction and movable in the driving direction.
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